Laterally connecting apparatus for veneer



April 16, 1968 TADASHI Al'zAwA LATERALLY CONNECTING APPARATUS FOR VENEER Filed Dec. e, 1965 3 Sheets-Sheet 1 @MTH Q P 1 968 TADASHI AlzAwA 3,378,430

LATERALLY CONNECTING APPARATUS FOR VENEER Fil ed Dec. 8, 1965 3 Sheets-Sheet 2.

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April 16, 1968 TADASHI AIZAWA' 1 3,

LATERALLY CONNECTING APPARATUS FOR VENEER Filed Dec. 8, 1965 I 5 Sheets-Sheet 5 '1 I n u 11 I II n u 1| [1 luul WINS/Ii Anna/ 7 IN uav 7v&

United States Patent 3,378,430 LATERALLY CONNECTING APPARATUS FOR VENEER Tadashi Aizawa, 24 S-chome, Datoku-Shinmachi, Minami-ku, Nagoya-shi, Aichi-ken, Japan Filed Dec. 8, 1965, Ser. No. 512,361 Claims priority, application Japan, Dec. 11, 1964, 39/ 69,401 Claims. (Cl. 156-556) The present invention relates to woodworking machines and more particularly to apparatus used to connect and seal together the edges of thin veneer strips with an adhesive to form a continuous sheet of veneer.

In conventional continuous veneer manufacturing ap paratus, individual pieces are prepared by proper drying of the veneer, cutting of their edges, and applying adhesive to one or both of the surfaces of their edges. In order to eliminate irregularities and to obtain a high degree of strength, is has been considered desirable to apply uniform heat over the entire surface of the veneer. The veneer strips are fed to a large vertical press having a rigid heating plate and an adjustable horizontal pressure is applied to the veneer pieces.

It is the objective of the present invention to provide an improved apparatus for the lateral or butt connection of veneer strips; which apparatus continuously forms large veneer sheets; which prov-ides increased strength and eliminates irregularities of veneer joints by preventing unstable rock-ing of the veneers during their feeding and sealing; and which avoids many material and technical difliculties inherent in the long, rigidly consrtucted heating plates used in conventional veneer manufacturing apparatus.

-In accordance with the present invention, apparatus is provided having a plurality of individual belts which continuously feed, heat and press the veneer pieces. The apparatus also includes a timing mechanism for peri odically changing the speed of the belts and mechanisms to periodically press the veneers to butt seal their edges. The required vertical and horizontal pressures are obtained by means of two sets of belts above and two sets of belts below the veneer and separate pressing mechanisms at the front and rear of the belts. The apparatus of the present invention butt seals veneers in a stable state without either disarrangement of the grain in the region of the joint or unstable rocking of the veneer during feeding and sealing.

Other objectives of the present invention will be ap parent from the description of the preferred embodiment of the invention given below, which is taken in conjunction with the accompany-ing drawings, in which:

FIG. 1 is a side sectional view of the preferred embodiment of the present invention;

FIG. 2 is a top plan view of the said embodiments;

FIG. 3 is a vertically sectioned elevation taken along line X-X of FIG. 2;

FIG. 4 is a side view of a periodic speeed-changing mechanism;

FIG. 5 is a side view of a periodic pressure applying mechanism; and

FIG. 6 is a wiring diagram of an electric heating system.

In FIGS. 1 and 2, veneer piece (strip) 1, which has been prepared by conventional methods, is inserted between belts 2, 2' above and belts 3, 3' below. The piece is to be butt sealed to the rear edge of veneer layer 4, which is composed of several pieces of veneer already connected into a single continuous sheet.

The belts 2 and 2 are supported above the veneer 4 on two sets of pulleys A and B, respectively. Similarly,

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the belts 3 and 3 are supported below said veneer on two other sets of pulleys A and B, respectively. Although the belts may be made of any sturdy heat and electrical conducting material, steel belts are preferred. The belts 2 are placed alternately with, and almost parallel to, the belts 2. The assembly of pulleys B and belts 2' are otfset toward the input of the machine (at the left in FIG. 1) with respect to the assembly of pulleys A and belts 2. Below the veneer 4, the belts 3 and 3' and the pulleys A and -B' are symmetrically arranged with belt 3 opposite belt 2, and belt 3' opposite belt 2. Each of the sets of opposing belts 2-3' and 2-3 are connected to the periodic speed-changing devices '6 and 6', respectively. The speed-changing devices 6 and 6 are connected to the motor 5.

Within the loops of belts 2-2 and 3-3 there are pressure plates 8 'and 8'. Heating elements 7 and 7' are attached to plates 8 and 3', respectively. Pressure plate 8 and heating elements 7', located within belts 3 and 3' below the veneer 4, are single stationary units. Pressure plate 8 and heating element 7 are divided into a plurality of sections symmetrically arranged within belts 2 and 2. There is one section of the pressure plate 8 and the heat ing element 7 for each of the individual belts 2 and 2. Each individual section of pressure plate 8 is attached either to the periodic pressure applying mechanism 9 or 9 and also to pressure mechanism 10 or 10'. Pressure mechanisms 9 and 9' control the pressure on the sections of pressure plate 8 adjacent to belt 2 and pressure mechanisms 10 and 10' control the pressure on the sections of pressure plate 8 adjacent to belt 2'. The pressure mechanisms 9 and 10 are located at the input end of pressure plate 8 and the pressure mechanisms 9" and 10' are located at the output end of the pressure .plate. The pressure mechanisms 9 and 9' are connected with speedchanging mechanisms 6 and the pressure mechanisms 10 and 10' are connected to speed-changing mechanism 6.

The speed-changing mechanisms 6 and 6' control the pressure mechanisms 9, 9', and 10, 10' in synchronism with their driving of the belts 2, 2' and 3, 3'.

The pressure between the upper and lower sets of belts 2, 2', 3 and 3 and the speed of said belts is synchronously varied so that the veneer 4 is vertically pressed with periodically high and low pressure.

The belts 2 and 3 and the belts 2 and 3 are driven so that belts 2 and 3 are driven at the same speed. Likewise, belts 2 are driven at the same speed as belts 3'. There is a phase difference in speed between the sets of belts 2-3 and the set 2- The pressure of the input and output sections of the same set of belts differs by 180". When belts 2-3 are at high speed, a high pressure is applied at the input section of belts 2. At the same time belts 2-3' are at 'a low speed, the input (front) section of belts 2' is under low pressure, and the output (back) section of belts 2 is under high pressure. Conversely, when belts 2'- are at a high speed, a high pressure is applied at their input sections. At that time belts 2-3 'are at a low speed, and their output section is under a high pressure. Thus, a braking force gradually acts on the output end of veneer 4 and a butting pressure is applied to the joints of veneer 4, first strongly and then Weakly, in a perodic manner. The heat from elements 7 and 7 together with the pressure applied through the belts 2, 2, 3 and 3 provides a butt joining action to veneer 4 (vertical and side pressure) simultaneously With a continuous feed of veneer.

One form of periodic speed-changing mechanism which is suitable for the present invention is shown in FIG. 4. An eccentric shaft sprocket 14 is located on the driving side, an ordinary concentric shaft sprocket 15 is on the driven side, a chain 16 is loosely wound and hung between said sprockets 14 and 15, and proper tension is applied to chain 16 by means of a tightener 17. The sprocket 15 on the driven side is driven at a periodically varying speed controlled by the amount of eccentricity of the sprocket 14 on the driving side. Further, the degree of eccentricity of the sprocket 14 can either be fixed or may be varied as required so that the speed-changing range of said periodic speed-changing mechanisms 6 and 6' say be adjustable. Other periodic speed-changing mechanisms known to those skilled in the art, such as staggered shafts or a fixed cam and link assembly, may be substituted for the mechanism described here and shown in FIG. 4. By adopting any such mechanism, the veneers 4 can be continuously fed at a periodically changing speed, first quickly and then slowly.

One form of mechanical pressure applying mechanism suitable for use in the present invention is shown in FIG. 5. A shaft which is driven eccentrically is located in socket 11, and the end of arm 12 is fixed by a pivot to the frame of the apparatus. The motion of the eccentric shaft is transmitted to the pressure plate 8 by a linkage having a top pivot and pivot 13. Further, the pressure applied by the periodic pressure applying mechanisms 9, 9, 10 and 10 can be fixedly or adjustably set by varying the location of the top pivot along the arm 12, or adjusting the amount of eccentricity of the mechanism associated with socket 11 or by changing the link having pivot 13.

When the pressure applied by mechanisms 9 and 10 to the input part of pressure plate 8 is higher than the pressure applied by mechanisms 9 and 10 to the output part of said plate 8, veneers 1 and 4- are joined by extrusion. When the pressure of the input part is lower than that of the output part, the veneers are joined by butting. Thus, it is possible to vary the type of joint made by the present invention to adapt to the veneers being joined.

Comparatively thick, stiff veneers may be joined by butting; and thinner, flexible veneers may be joined by extrusion. It is also possible to adjust the butting pressure applied so that a comparatively high pressure may be ap plied to veneers in which the cut surface is not straight or the edge is rough. In some cases it is possible to indirectly adjust the butting pressure by changing the relative speed ranges of the belts 2, 2, 3 and 3 by adjustment of the speed-changing mechanisms 6 and 6'.

The requirements of the heating elements 7 and 7 are that they present unstable rocking of the veneer 4, generate or transmit heat rapidly, and apply presssure to the belts 2, 3, 2 and 3 and to the veneer 4 with a low coefiicient of friction. It is also necessary that the means of supplying energy to the heating elements 7 and 7 be simple, that the required temperature be uniform over the entire surface, and that the vertical pressure not be varied by thermal strain. The type of device preferred for this application is a sheet material, such as a graphite or a fluorine resin sheet, having the required properties of heat resistance, thermal conductivity, flexibility and smoothness. The sheet is glued to the surface of a heating plate. The plate is heated from the inside by steam, hot water, hot gas or electricity. The plate is pressed against the belts 2, 3, 2 and 3'. An example of a suitable material for heating elements 7 and 7 is a molded plastic sheet containing semi-conductive carbon black. The sheet has a specific gravity of 1.1 to 1.2, a hardness of 4 to 6 kg./cm. a bending breaking strength of 200 to 300 kg./cm. a coefiicient of friction of 0.1 to 0.5, a Wear resistance coefiicient of 500, an electrical resistance rate of 0.001 to 0.2 ohm/cm., and a thermal conductivity of 10 to 30 kcal./m. hr. C. Such a material and device is described in the present inventors prior Japanese Patent No. 401,355 (publication No. 3,275/1962). It may be made by mixing a graphite (carbon black) material in a ratio of 1:10 with a fibrous material suspended in Water, to which an emulsion of a synthetic plastic resin has been added. The water is drained, forming the mixture into a mat which is then heated and pressed to form a molded sheet. The electrical resistance can be varied over a wide range by varying the proportion of graphite powder to fibrous material so that a comparatively high electrical resistance direct heating system may be obtained. Referring to FIG. 6, the heating elements 7 and 7 are in contact with the belts 2, 2, 3 and 3. Preferably an electric current is fed in parallel to electrodes 19 and 19' which are on the back surfaces of heating elements 7 and 7. The current flows through the heating elements and returns to the alternating current source 18 by means of conductive belts 2, 2, 3 and 3. As shown in FIG. 6, there is only one lead to the bottom heater 7 and another lead to the top heating elements 7. The return paths are not shown. The connections between the upper heating elements 7 and the electrodes 19 permit individual vertical movements by the periodic pressure applying mechanisms 9, 9', 10 and 10'. Heat-proof electric insulators 20 and 20' are provided between the pressure plates 8 and 8 and the electrodes 19 and 19' to prevent an electrical short circuit.

Besides the modes of operation described above, it is possible to achieve additional modes of operation by variation of the phase relationship between the feeding speed and pressing forces, using devices such as a stepless phase adjusting mechanism. Moreover, the mechanical periodic pressure mechanism described may be replaced by other mechanical, hydraulic, or air-pressure periodic pessure mechanisms. For example, the rotation period of the periodic speed changing mechanism may be connected to the control valve of said hydraulic or air-pressure type mechanisms either by mechanical means or through such electrical control circuits as limit switches. Further, the adhesive applied to the joints of the respective sheets may be replaced with gummed tapes, and the same operation and results may be obtained. Other modifications of the present invention are within the scope of the subjoined claims. For example, other controlling mechanisms, power transmitting mechanisms, joining systems, and the kinds of material handled will be obvious to one skilled in the art. As an alternative, only the top belts may be used and the bottom veneer support may consist of free-wheeling rollers.

I claim:

1. A butt sealing apparatus for veneer manufacture comprising a first set of rollers and a second set of rollers; a plurality of belts wound about the first set of rollers and a plurality of belts wound about said second set of rollers, the belts on the first rollers being interleaved with the belts on the second rollers; means to drive said first and second rollers with a phase difference in speed between first and second rollers and at variable speeds so that the speed of each set of belts may be fast or slow; and a plurality of pressure means associated with each belt to apply pressure periodically, said pressure means being positioned inside said belts and divided into an input section and an output section, the pressing force on the belts of the first roller having a phase difference in relationship to the pressing force on the belts of the second roller and each belt being periodically pressed in its input section and its output section by its associated pressing means; wherein the pressing force of each of said pressure applying means is directly proportional to change in speed of its associated belt in its input section and inversely proportional in its output section.

2. A butt sealing apparatus as set forth in claim 1 and also comprising a third and a fourth set of rollers positioned beneath said first and second sets of rollers, a plurality of belts on said third rollers and a plurality of belts on said fourth rollers, the belts on said third rollers being interleaved with the belts on said fourth rollers, and driving means to rotate said rollers at variable speeds.

3. A butt sealing apparatus as set forth in claim 1 and also including a pressure applying means and heating means to apply pressure and heat to the belts on said third and fourth rollers.

4. A butt sealing apparatus as set forth in claim 1 and including heating means to heat said belts and thereby heat the veneer.

5. A butt sealing apparatus as set forth in claim 4 in which said belts are made of a heat conducting material.

6. A butt sealing apparatus as set forth in claim 5 in which said belts are made of steel.

7. A butt sealing apparatus as set forth in claim 4 in which the heating elements are electrical heating elements.

8. A butt sealing apparatus as set forth in claim 4 in which the heating means are individual elements associated with each belt and composed of plastic resin and conductive carbon.

9. A butt sealing apparatus as set forth in claim 1 in which the phase difference between the pressing force applied to the input section and that applied to the output section is 180.

10. A butt sealing apparatus as set forth in claim 1 in which said belts are conductive and part of the electrical circuit for said heating elements.

References Cited UNITED STATES PATENTS 3,021,248 2/1962 Mann et al. 156274 EARL M. BERGERT, Primary Examiner. M. L. KATZ, Assistant Examiner. 

1. A BUTT SEALING APPARATUS FOR VENEER MANUFACTURE COMPRISING A FIRST SET OF ROLLERS AND A SECOND SET OF ROLLERS; A PLURALITY OF BELTS WOUND ABOUT THE FIRST SET OF ROLLERS AND A PLURALITY OF BELTS WOUND ABOUT SAID SECOND SET OF ROLLERS, THE BELTS ON THE FIRST ROLLERS BEING INTERLEAVED WITH THE BELTS ON THE SECOND ROLLERS; MEANS TO DRIVE SAID FIRST AND SECOND ROLLERS WITH A PHASE DIFFERENCE IN SPEED BETWEEN FIRST AND SECOND ROLLERS AND AT VARIABLE SPEEDS SO THAT THE SPEED OF EACH SET OF BELTS MAY BE FAST OR SLOW; AND A PLURALITY OF PRESSURE MEANS ASSOCIATED WITH EACH BELT TO APPLY PRESSURE PERIODICALLY, SAID PRESSURE MEANS BEING POSITIONED INSIDE SAID BELTS AND DIVIDED INTO AN INPUT SECTION AND AN OUTPUT SECTION, THE PRESSING FORCE ON THE BELTS OF THE FIRST ROLLER HAVING A PHASE DIFFERENCE IN RELATIONSHIP TO THE PRESSING FORCE ON THE BELTS OF THE SECOND ROLLER AND EACH BELT BEING PERIODICALLY PRESSED IN ITS INPUT SECTION AND ITS OUTPUT SECTION BY ITS ASSOCIATED PRESSING MEANS; WHEREIN THE PRESSING FORCE OF EACH OF SAID PRESSURE APPLYING MEANS IS DIRECTLY PROPORTIONAL TO CHANGE IN SPEED OF ITS ASSOCIATED BELT IN ITS INPUT SECTION AND INVERSELY PROPORTIONAL IN ITS OUTPUT SECTION. 